Explosive operated motor for rip cord



14, 1951 D. F. MURPHY 64,209

EXPLOSIVE OPERATED MOTOR FOR RIP CORD Filed Jan. 25, 1950 2 Sheets-Sheet 1 N INVENTOR 9: I Donald FMJI Did k BY M 6 @645;

ATTORNEY 14, 9 D. F. MURPHY ,564,2

EXPLOSIVE OPERATED MOTOR FOR RIP CORD Filed Jan. 25 1950 2 Sheets-Sheet 2 INVENTOR BY M 6 0 M.

ATTORNEY IIED STATES PATENT OJ'FLFi-I'JCE .EXPLOSIV E. OPERATED; MOTOR .EOR "RIP CORD .Donald Francis Murphy, Baltimore, Md.,.assignor to Bendix Aviation Corporation, :Baltimore, Md., :a corporation of Delaware "Applieationflanuary 25, 1950; Serial N 0. 1403520 "TClaims. 1 This invention relates to improvements=in'-the .design'of-explosive devices of the type wherein an ,-.expansibleibellows confines an-explosive powder ;chargerand is: adapted to 1 beexpanded upon {ignition.xofthezzpowder charge, the r-forces of explosionzbeingsuiiicientitmexpand the: bellows, but insufiicient; toaeause rupture: thereof whereby the gases and :residue iresulting :from explosion are sconfined Within?thB fbE110WS. .The. improvements :achieved result inza unitary, rugged, and comipa-ct. device .suitable for" large quantity manufacture "at low cost rand shaving :features of design .permittingseasezand fiexibilityxof use.

Heretofore, devices 70f this :type were "made up etan-assemblyqrof .-'a number ofrdifferent parts, 1

thepartsrequiring a;-substantia1 number-of ma- 1 chiningpperationsito permit same: to :be. properly assembled. ;-Moreover, a grounded ::system was msedwherein the hase cfthe device constituted "one elect-rodeand carried therein: insulated there- "IIQm,--the otherelectrode. :Additionally, cumber- 1 some ,threadedrpa rtsrequiring wrenches iorftigli :ening were used :to lock the device in an *actuating .mechanism. :Such :a .device iis Jshown in 1U. 15. Patent :No. 2.5104148 iissued .April :18, 1950. iThe present invention is .rdirected to improvements in the device shown in the Ogdenvetal.vapplication. The improvements have'resulted in a reduction of the number of :parts, :a reduction in rthe"manufacturing operations required, the subwsti-tution of re. two-wire electrical system 'per- -mitting' the'use'of more simple and positive elecstricalconnections-to an "external source of supply, a reduction :inisize'and weight, all "of which result in a very compact assembly 'capable of "being manufactured at low-'costs:"and capable of .being'used-in a'varie-ty of applications with=a \ma-ximum of ease.

',Th invention'will be morecl'early understood .by reference to the drawings annexedi'hereto fin .which:

:Eig. 1 iS'ZrCIOSSeSQCtiOHfll view "of one embodiment of the? invention; 1

Fig. .2 is a view .taken "along the 3 lines 2 2 in Fig. 1.

Fig.3 .is a cross-sectional view of another-em- .bodiment of the invention;

Fig. 4 is a view ta-kenalong the lines 44-'in (Fig. 3; and

Fig. 5 is a view-partially in section, showingcthe .manner'in which the embodim'ent disclosediin Fig. v1 can be @used in conjunction with :an automatic parachute opening device.

Referring now to Fig. 1, it is seen :that the ,vdevice comprises substantially a .two-partassem- 'bly" of a flexible metallic bellows' fi and a 'molded plastic base I.- The bellows ifi has rigidly secured 'to its open end, as '"by 'brazing or soldering, the annular shoulder membert for 'receiving'the base l therein. .Althou'gh 'the bellows 26 .andizshoulder member 8 are shown as comprising aitwo-part assembly, the combinationircouldabet-achieved by a singlepart however, except fontrelati-velyismall diameter bellows, iitiisi less-.iexpensive to :make up the combination IfromItWo :separate parts. :The outer edges!) :of thershouldertscarezrolied over to rigidly c-secure it-he ibase' T130 .i-the 9 bellows "6. 'A coating :of .-'sealing rcompound :may be applied to thejunction of: edge! and base "I.

zThelbase I has za 'centrally'disclosed portion I I of reduced diameter,:whichprojects into themteriorvof the bellows 6. The base 111s cutsaway on its outer side atozform the centrallydisposed 'recess I2. .The innerextremity I--3-of the portion I I is-reduced furtherin diameter: andserves asiaesupport i'for 'theffrangibe cap I4 which. may besui-tably'afiixedto the: extremity t3. 'Ihe base I is provided with 19,.132111 of electrodes I5, 16, whichextend from both fa'cesithereof. "Iheiinner and 1.0111381 :extremities of the electrodes =I5, -15,

'areiof slightlyreducedfdiameterrand thelinterior portionsof --the-.e1ectrodes I5, I 6 may be :rough ened or knurled throughout .a portion ef the length 1 to "provide a positive 1 mounting within the base. Normally, =.base 1EOH1QIY1S8S wwaterproof thermosetting plastic material; and the :electrodes I5, I5 are securelyefiixed twthebasexduring the "molding of same.

The'outer extremities of the electrodes IE, it, do not projectbeyondthe ;outeriface of-thebase I. That is to say, they lie wholly within. the recess 12. Thus, Ce. compact cartridge-type device .is'achieved, having no parts protruding'or extending beyond the outer surface ofbase =1.

"The inner extremities :of the -.electrodes I5, I I5 have a'filament IIbridging their gap,-to which -is affixed :a priming head 48. "A :suitable ,POWdBI charge "can .be placed within -'the cap I i, and is :compa'cted therein so -as to surround the electrodes I5, I 6 andsubstantially fill =up 117118 volume .confined by the cap I4. Thebuter extremities of the electrodes J5, I6 arez-adapted to beconnected .to .a source of electrical energy 'Ythrough suitable rswitchin'g means and, upon O1OS11I'B=Df the :circuit and consequent "application of energy to the -electrodes,1a'current =willtfiovrthrough the-electrodes by reasoncofthetfilamerit I1 bridging the gap "between :their inner extremities. The "filament .'I is selected to provide 1a Thigh 'selectrical 'iresistance that passage :of current therethrough will cause a substantial degree of self-heating. The filament M will continue to heat until the priming bead l8 ignites, which in turn causes the powder confined within the cap l4 to ignite 'and explode. The cap I4 is readily disintegrated by the explosion of the powder contained within and permits the explosive gases generated to flow into the interior of the bellows 6. Ordinarily, the base 1 of the device is rigidly secured with respect to a fixed support, so that the forces generated by the explosive gases will react upon the inner end of the bellows B in such a manner as to expand the bellows toits permissible length. Thus, it is seen that the bellows 6 is readily expanded by explosion of the powder charge confined therein. Because the bellows 6 and base 1 are rigidly secured together, all of the explosive gases, any flame or heat flashes, and all of the residue resulting from the explosion are confined within the bellows. As is known in the art of automatic parachute opening devices, such a construction is ideal, so that the parts and materials associated with the explosive device are not injured or damaged by the resulting flame and explosion.

In Fig. 3, the embodiment shown therein is substantially the same as that shown in Fig. 1, except for the fact that the recess |2, shown in Fig. 1, has been eliminated and the bellows and its base retaining rim are in one piece. Thus, in Fig. 3, the base 2| has affixed thereto the flexible metallic bellows 22, the open end of the bellows (retaining rim) forming an annular shoulder 23, the outer edges 24 of which are rolled over on the outer face of the base 2|. A suitable sealing compound may be applied at the junction of edges 24 and base 2|. The base 2| has an inner portion 25 of reduced diameter, and this portion 25 forms a support for a frangible cap 26. A pair of electrodes 21, 28 are carried by the base 2| and afiixed thereto in a manner asdescribed in connection with the embodiment shown in Fig. 1. The inner extremities of the electrode 21, 28 are bridged by a filament 29, which has a high value of electrical resistance and upon connection of the outer extremities of electrode 21, 28 with a source of electrical energy, the current passing through the filament 29 causes same to heat, which in turn results in ignition of the priming bead 3|, which causes the powder charge confined within cap 25 to ignite and explode, and thereby expand the bellows 22 to its permissible length. The operation of the embodiment shown in Fig. 3 is identical with the operation of the embodiment shown in Fig. 1. Ordinarily, the embodiment shown in Fig. 3 is useful, for applications requiring a general y smaller explosive device.

In both embodiments of the invention, the priming bead and powder charge are sul hur base materials characterized by a very rapid burning rate. The caps confining the bead and charge may be acetate material, and a l-volt source of electrical energy will provide s fiicient power for energi'zation of the device. The embodiment shown in Fig. 1 may have a bellows diameter on the order of /1" and a total possible elongation of two inches. With such an arran ement. and the proper selection of the quantity and type of owder charge uti ized therewith, a force of 100 pounds can be developed for one inch of elongation. In Fig. 3, the bellows diameter may be on the order of one-half inch, with a total possible elongation of one inch. In

this embodiment, with the proper selection of quantity and type of powder charge, a force of pounds can be developed for three-eighths of an inch elongation.

In Fig. 5, there is shown a portion of an automatic parachute opening device adapted to be actuated by the embodiment of the invention shown in Fig. 1. Thus, there is shown a barrel 32 having a bore which in turn, has the annular shoulder 33, upon which the outer extremity of base 1 rests. The bellows 6 projects into the bore 30 and rests against a piston 34, which is rigidly secured to a pulley 35 by means of guide pin 38. A pair of slots 36, 31 in the bar rel 32 permit the pulley 35 to move therein. The pulley 35 has an arcuate slot 39 through which passes a flexible cable 4|, one end of which may be suitably clamped in a fixed 'posi-.

tion with respect to barrel 32, the other end of which may be affixed to the ripcord of a parachute. The barrel 32 has a pair of plates 42, 43 suitably aifixed, as by brazing, to its inner and outer extremities, respectively, to which are secured a side member 44 and top 45, all of which provide a compact housing for the device.

Cooperating with the projecting electrodes l5, l6 of. the explosive device, there is a conventional type of electrical socket 46 having a pair of apertures for receiving therein the electrodes l5, l6. Suitable spring clips 41 are located within the apertures to firmly grip the electrodes |5, l6 and provide good electrical contact therebetween. The spring clips 41 extend from the socket 45 and are connected to a pair of electrical leads 48 which, in turn, are adapted to be connected to a source of electrical energy through suitable switching arrangements. The socket 46 is carried by a breech member 49 whose inner extremity takes the form of an annular flange 5|, one surface of which is adapted to abut against the outer face of the base 1. Surrounding the breech 49 is a lock-nut 52 which cooperates with threads provided in the outer extremity of bore 32. The lock-nut 52 is adapted to be inserted into barrel 32 and screwed therein until the breech and base 1 are tightly clamped into the bore 30.

With the above arran ement of parts in mind, it is s en that the base 1 of the ex osive device is rigidly fixed with respect to barrel 32, and upon explosion, the inner end of bellows 5 will travel inwardly, carry ng with it the piston 34 and its associat d pi llev 35, which in t rn will ex rt a force on the cable 4!. thereby opening the parachute associated the ewith.

It is to be note that in both embodiments of the invention, the base members 1 and 2|. respecti ely. may be formed o a w terroof plas ic material having electr cal insulat ng ro e ties and easily molded into the sha e and configurat on desi ed. In th form of the device sho n in Fig. 1, the recess l2 provides a comp ementary portion of the base 1 for insertion there n of the socket 4B. In either embodiment of the invention, the explosive device can be readl and easily slipped into a bore and clamped thereto by simplified breeching arrangements, not requiring any awkward wrenching operations.

What is claimed and des red to be secured by United States Letters Patent is:

1. In an explosive device, in combinat on: an annular base member having a centrally disposed portion of reduced diameter, said base member being composed of an insulating material; a pair of spaced electrodes carried by said base member and extending axially therein, whereby the extremities of said electrodes extend outwardly from opposite faces of said base; a conductive filament carried by the inner extremities of said conductive pair, said filament having a priming bead se- 5 the volume defined by said cap and base member; 10

a flexible metallic bellows surrounding said centrally disposed portion and having a closed end and an open end, said bellows being adapted to expand under influence of the forces generated by ignition of said powder charge said open end having the configuration of an annular shoulder for receiving said base member therein, the outer edges of said open end of said bellows being rolled over on the outer side of said base member, whereby anintegral assembly is achieved. 29

2. The combination defined in claim 1, wherein said base and said electrodes comprise an integral assembly formed by molding a water-proof thermosetting plastic material around said electrodes.

3. The combination defined in claim 2, wherein a sealing compound is applied to the junction of the outer side of said base member and the'rolledover edge of said bellows.

4. The combination defined in claim 3, wherein the outer side of said base has a centrally disposed recess surrounding said electrodes, and the exposed extremities of said electrodes extend from said recess, but do not extend beyond said outer side. 35

5. The combination defined in claim 4, wherein an electrical socket is provided to receive the exposed end of said electrodes, said socket having a configuration complementary to the configura- 40 tion of the outer side of said base.

6; in an explosive device, in combination: an annular base; a flexible metallic bellows having an open end and a closed end, said open end being rigidly and hermetically secured to said base; powder charge force generating means within said bellows and carried by said base; and powder charge igniting means within said bellows and carried by said base, said bellows being adapted to expand under influence of the forces generated by ignition of said powder charge and said last-named means comprising a pair of electrodes extending in an axial direction through said base on both sides thereof; insulating means surrounding said electrodes, a conductive filament bridging the inner extremities of said electrodes, and a priming bead affixed to said filament.

7. The combination defined in claim 6, wherein the outer side of said base has a centrally disposed recess surrounding said electrodes, and the exposed extremities of said electrodes extend from said recess, but do not extend beyond said outer side.

DONALD FRANCIS MURPHY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,660,713 Kauch Feb. 28, 1928 1,892,050 Goss Dec. 27, 1932 1,933,694 Allen Nov. 7, 1933 2,393,629 Grant Jan. 29, 1946 FOREIGN PATENTS Number Country Date 585,265 Great Britain Feb. 3, 1947 

